The film follows Eckhart's Staff Sergeant Michael Nantz as his platoon heads into the bombed out ruins of Santa Monica to find any survivors of a devastating - and ongoing - alien invasion. As cities around the world fall to the mysterious invaders, this one platoon takes on the foolhardy task of saving Los Angeles from total annihilation.

Last week, we had the chance to visit a very un-destroyed Santa Monica to talk with director Jonathan Liebesman and stars about the movie's origins, the intense pre-filming boot camp, and where this story could go next.

Aaron Eckhart explained to us how he got involved with the project and why this was a movie he wanted to make:

I got the script from my agent and it was kind of just an alien movie, you know, and I very [uncertain], and Jonathan [Liebesman] didn't have the job yet, but he was making a play for it. And so I met him, and he had done all these mock-ups of aliens on his computer just using kind of generic software and [it was] very impressive stuff. And at the end Jonathan showed me a page of YouTube and it was Marines going house to house in Fallujah. And it was both organized yet chaotic because it was unpredictable, you know, these guys showed their training and showed their youth. And Jonathan said, "This is what the movie's going to look like," and I said, right then and there, I said, "I'm in. I will die for this part." And I feel like through the filming and to the final cut that we achieved that goal, which the goal was this is a war movie, a documentary kind of war movie with aliens in it. And that, for me, I was like a kid in a candy store.

Still, Eckhart was quick to delineate between the real horrors of war and him and a bunch of actors getting to play make-believe. Indeed, he sees one of the primary functions of this movie being a tribute to the armed forces and the great sacrifice of those who serve their country:

This is an entertaining movie, but I hope it's an homage to that, I hope it shows some sort of, you know, reflection, some sort of history, a toll is taken. This movie, in my opinion, is meant to be a love letter to the Marines. We had their full cooperation, they had my full cooperation, I tried to get it right. I think this movie is very reverent towards the military and reverent towards the ranks, both the officers and the grunts. I don't see how any Marine can see this movie and feel at all taken advantage of. I think this is going to be an "Ooh-rah" moment for them, and I'm going to Quantico, going down to San Diego, these guys are going to love this movie.

Director Jonathan Liebesman explained why he thinks alien movies have such an enduring appeal, particularly when it's possible to wed them with the war movie genre:

I'm fascinated by outer space, we all wonder if there are aliens, if they are and they come to visit us are they going to come fuck us up or come in peace. I think it's great to have a common enemy, you know, where everyone can come together and fight the same thing and there's no politics and we all go through the experience of being shocked and awed. And I think that's a common fear. I know I felt it on 9/11 when I saw the news report and I saw what was happening and other people have felt it since around the world. At least with aliens you all get to get behind the same team. So I think that [movies with] aliens will always be around, always.

As he explained, a ton of thought went into making the aliens a realistic, credible threat - but, crucially, not too threatening:

I think the take we did on the aliens and it was important to me was that even though they've come from outer space, how can we ground this so they don't destroy us in four seconds? And I think with the designs we tried to create something that you understand that even though they're further than us in certain ways they're the same as us in other ways. There was a big deal to maintain a credibility of why we don't get wiped out in four seconds. So there are certain things - they're a very used up army, they've probably fought a bunch of wars, they're probably exhausted too, they get injured, they're not invincible - and that was a big aspect.

]The movie was shot on location in Shreveport, Louisiana - as Aaron Eckhart explained, there's not much actual movie-making in Los Angeles these day outside the studio lots, and there's no way they could get away with simulating this much urban destruction in LA itself. To get ready for their military roles, all the Marines (as well as Michelle Rodriguez's Air Force sergeant) attended "boot camp" to get them in the right physical and mental shape. Eckhart says this training was absolutely crucial:

First and foremost, the training was the most important thing. I trained for months working with weaponry and with the physical aspects of being a Marine in this situation. Also, getting to know the Marines, getting to know the heirarchy, the mentality, the psychology. And then we went through boot camp, three weeks in the middle of Louisiana, hotter than hell, we slept in tents, we ate in rank, all that sort of thing, showered, the whole deal. Which was interesting, because we went from a bunch of actors who didn't know each other, some who had experience and some who hadn't, and suddenly we had to forget that we were actors and go into this very regimented workout scheme. And it was interesting how far some actors would go and how much they would buy into it and believe it. Because when you're out there and I'm yelling at you in character, the actor's like, "Dude, I'm just an actor!" [Laughs] It was a good way to sort of erase our real lives and get into character, which helped immensely in the movie.

Battle: Los Angeles leaves the attacking aliens very much a mystery, not revealing much about them beyond what it takes to kill them. As Liebesman explains, this was a function of the story they were telling, but when we asked him about how much thought went into the deeper backstory of the aliens, he explained:

There was a hell of a lot. There was a guy named Ty Ellington who helped us design who works a lot with [James] Cameron, he even goes as far back as A.I when [Stanley] Kubrick was doing it, and we formulated a whole story of where the aliens come from, what their planet's like, why did they come here, why do they need specific resources, so it's stuff that was very interesting to me and less important, less interesting to other people.

He then explained that these are the sorts of things he'd love to expand upon in a sequel:

But if there's a sequel to the movie, if the movie made enough money and people want to see something, there's a whole wealth of stuff I'd want to bring. This was a movie that was just a simple search and rescue mission, I think there's a whole lot more interesting stuff that was not done here that could be done in a sequel. [In a sequel] we can get into some more issues, some moral issues, but again, this was just an in-and-out experience, this movie, more of an entertaining fun thing. I think there's a whole world ahead of me that hasn't been touched that hopefully can.

Aaron Eckhart was very clear that he'd love to do a sequel, and he's hopeful that a sequel can turn this into an international, globe-hopping adventure, although he admits that might be a challenge:

I think we're thinking bigger than [the US]. I think we're thinking like Paris, Tokyo, Rio, you know we've got to think of places we all want to go to...and then we'll go to Vancouver. [Laughs] How would we make Shreveport look like Paris? Lots of baguettes and chapeaus...You couldn't shoot a movie like this [in Paris].

When we asked Michelle Rodriguez where she would like to for a sequel, she was a little more realistic about where Marines could go. But, like Eckhart, she'd like to not have to return to the incredible heat of Shreveport:

I wish it was some foreign country but we're defending America, aren't we? So it would have to be here. And if it were here, hmm, where...there's so many cool places...Miami! I want to go someplace warm...wait, Miami would be really, really hot in those outfits, so somewhere cold...Can we do Battle: Los Angeles... in spring? Like that'd be great.

She also considered the possibility of Battle: New York, which she said would be epic, but decided that it's probably still too soon to do any sort of mass destruction like this in New York City. This was a point that costar - and World Trade Center actor - Michael Peña very much seconded, saying that urban destruction like that seen in Battle: Los Angeles needs to be warranted by the story, and not just there for shock value.

Indeed, that was a point that everyone stressed - yes, this is trying to be a realistic war movie, and Jonathan Liebesman explained it borrows freely from real war images, but this is ultimately about making an entertaining action movie, and no disrespect is intended. Indeed, Liebesman explained how he drew on everything from real images of war to his favorite video games:

On the reality front, there was a lot of embedded Iraq footage, a huge amount of that was looked at and Vietnam War photos. On the movie front, movies as recent as District 9 or Black Hawk Down, Saving Private Ryan, all those kinds of thing were inspirational. Then things such as, I think there's some amazing visuals and work that goes into video games, Halo, Call of Duty, Gears of War, there's some amazing design on stuff. So it was just everything I was interested in I tried to synthesize.